I main supports. I do a job good enough, by feeding my AD carry, denying the other bot lane, roaming or pulling off clutch support moves, to "carry" the game more often than not. The one exception to that rule is Ezreal. Unlike other AD carries, I don't feel I make anything happen with Ezreal other than hope he is good enough to out-play our opponents.
From my point of view, he has poor harass and poor burst. I can't play a kill lane Leona or Alistar as we'll likely get out-DPSed. I can't play a passive Soraka, but it feels like we're getting denied too easily. Blitzcank is about the only support I have had some success with, but even there it feels considerably more difficult than when I play Blitzcrank with other lane partners. Ezreal really feels like laning with a bad Corki.